The capability to support high-speed mobile packet data traffic is one of the most important characteristics of the 3G system. 3GPP R99 may provide a data rate with a peak rate of 2 Mbps. Such a rate can meet the requirements of most of the existing packet data traffic transmission. However, for many data services with strict requirements on traffic load and delay, such as video, streaming media and downloading, the system is required to provide higher transmission rate and shorter time delay.
Therefore, HSDPA technology is a technology introduced into R5 by 3GPP HSDPA not only can support high-speed asymmetrical data service, but also can greatly increase the network capacity and minimize the input cost of operators at the same time. It provides a way to smoothly evolve into higher data transmission rate and higher capacity for a Universal Mobile Telecommunications System (UMTS). In HSDPA technology of 3GPP R5, full reference is made to the design philosophy and experience of CDMA20001X EV-DO, and a high-speed downlink shared channel (HS-DSCH) is newly added. With the HS-DSCH, resources may be uniformly utilized, and may be dynamically allocated according to the actual situation of users. Accordingly, the resources efficiency may be improved.
In the existing single-carrier HSDPA, when a packet data is transmitted, the network side sends control information to a user equipment via an HS-SCCH channel (downlink control channel) in advance. The control information is used by the user equipment to receive data sent by the network side via an HS-DSCH channel, including information about data blocks sent to the user equipment on the HS-DSCH channel, information about time slots employed, modulation mode, data block size, redundancy version number and retransmission version etc. Then, the network side performs traffic channel (HS-DSCH) coding on the data to be sent and then sends the data. The user equipment obtains the control information from the HS-SCCH channel, and then decodes the data received from the HS-DSCH channel using the control information.
Referring to FIG. 1, it is a flow chart of a method for single-carrier HSDPA traffic channel coding in the prior art, which includes the following steps:
S110 (CRC Attachment): A CRC check bit is attached to a data block to be sent, by means of which a user equipment may check whether an error occurs in the received data;
S120 (Code Block Segmentation): The data block is segmented according to its length, which is a pre-processing of the subsequent channel coding;
130 (Channel coding): Channel coding is performed on the segmented data block, so that the receiving end may correct most of the errors during transmission according to the channel coding;
140 (Rate Matching): Rate matching is performed twice on the coded data, so that HARQ transmission may be carried out;
S150 (Data Scrambling): The data subjected to the matching processing is scrambled, so that the data to be sent will be further randomized, thereby the transmission performance will be improved and mutual interference will be reduced;
S160 (Data Interleaving): The scrambled data is interleaved, and the interleaved data is sent in different time slots, thereby time diversity gain will be obtained and the robust capability will be improved;
S170 (16QAM Constellation Rearrangement); When the modulation mode of the data transmission is 16 QAM mode, if retransmission occurs, the high and low bits of the constellation point for the retransmitted data need to be exchanged, thus the performance of high bit data and low bit data in the constellation point may be balanced.
S180 (Physical Channel Mapping): The data to be sent are adapted to different physical channels for transmission.
To further improve the performance of the system, the applicant proposes a solution to enhance the packet data traffic transmission capability via multi-carrier HSDPA technology. However, in the current 3GPP TDD R5 specification, only employing HSDPA single-carrier transmission mode for the method for multi-carrier HSDPA traffic transmission channel coding cannot meet multi-carrier HSDPA data transmission.